The PC-98 series can be pretty daunting to work with, mostly because, much like its IBM counterpart, it's a platform that lasted for a really long time (around two decades), and in that time it changed gradually while an immense amount of software and hardware was developed for it. This guide will try to make sense of some of that insanity.
First off, you need to choose a platform. The PC-98 series is mainly divided into two "generations": the original models which use NEC's μPD7220 "GDC" as their video controller (limited to 640x400 with 16 colors), and later models (mainly, but not limited to, the PC-9821 series), which add an enhanced GPU called EGC that can handle 256 simultaneous colors, among other things.
As of the writing of this guide, the recommended "old" model to work with in MAME is the PC-9801RS, and the recommended "new" model is the PC-9821Ce2. Those run reasonably well for our purposes.
Also, running old games from floppy is easy enough, but if you want to run post-1990 stuff, you will probably want to install DOS into a hard disk image, so the first thing to do is creating it with CHDMAN. For example:
chdman createhd -o path_to_your_hdd_image.chd -chs x,y,z -c none
...where x, y and z are the disk geometry (cylinders,heads,sectors). The machine won't care too much about the exact numbers, so you can just put something that lands you in the ballpark of the size you want. For example, "2048,16,63" will get you a 1 GB CHD. PC-98 DOS handles large HDDs pretty well, so don't worry about going too high.Installing MS-DOS
To start the installation, we need to do a couple things:
First, run MAME with just the basic parameters for a PC-98 driver. For example, "mame pc9821ce2".
It will fail to boot but we don't care about that yet. Go to the TAB menu and select "Machine Configuration". You will see an option named "Load IDE BIOS", enable it and press ESC a few times until you exit the emulator completely.
Now the driver is configured to be able to use the HDD image. Run MAME again but this time mount the HDD image and the first MS-DOS 6.2 floppy from the software list:
mame pc9821ce2 -hard1 path_to_your_hdd_image.chd -flop1 msdos62:flop1
If everything is OK, you will see this:
This screen is asking if you want to install DOS on a hard disk (固定ディスク) or floppy disks (フロッピーディスク), so choose the first option.
This says that the disk isn't initialized, so you need to initialize (初期化) it. Just press ENTER.
(By the way, this is a good time to remind you that you can use the F10 key to unthrottle the emulation and let it run as fast as your host computer can handle. Trust me, you will need it.)
Here you choose the size of the DOS partition. Since we're simplifying things, just leave the default (the whole disk) and press ENTER... but just in case you want to do more complex things later, you might want to know that PC-98 systems use a custom partition layout that is very straightforward and flexible: all partitions are equal (no primary/extended stuff), you can have up to 16 of them per disk, and any of them can be bootable. All PC-98 formatted HDDs include a boot manager embedded in the MBR that appears whenever you have more than one bootable partition, and you can use it to boot anything from anywhere, without any limitations!
Anyway, the installer will ask you to confirm that yes (はい), you want to create the partition, or no (いいえ), you want to go back.
It will create and format the partition...
And it's supposed to automatically reset the machine, but this doesn't work in MAME so you will see a rather scary "SYSTEM SHUTDOWN" message. Get used to it.
So just press F3 in partial keyboard mode, and the emulated PC-98 will reset and boot from floppy again.
The installer will run again and ask for an installation directory. You can just accept the default, ¥DOS.
(NOTE: due to some weird historical shenanigans, the standard path delimiter in Japanese DOS computers is "¥" instead of "\". Don't ask.)
Confirm again (はい), and it will start to copy files from disk 1.
After that, it will ask for System Disk 2 (システムディスク＃２), so go to the TAB menu, File Manager, Floppy disk 1 (you should see all MS-DOS 6.2 disks at this point) and choose Disk 2.
You will see the same screen for each of the 8 disks, so keep changing them as the installer asks.
When it finishes, this screen will gladly inform you that some OS features (like printer support or XMS memory) will be enabled by default, while others (CD-ROM support, HDD cache) will not, and you can customize that with the CUSTOM command, which is the first clear sign that this isn't quite like the DOS we are all used to. More on that later. For now, just press ENTER.
The installer is finished! Remove the floppy disk from the drive and press ENTER. You will get the SYSTEM SHUTDOWN screen again, so press F3 and boot from your shiny new DOS installation... into the "beloved" DOS shell that Microsoft wanted to push on everyone back then. For now, go to the File (ファイル) menu and choose the last option (終了, or Finish).
Now you're on the familiar DOS prompt. You could start running porn games on it right away (don't lie to me, if you're using a PC-98 that's pretty much a given) but in the next post we will do a few things to customize the system for our needs.
(continued on the next post...)